Pregnancy-associated growth factor (PAGF), an 18,000-22,000 MW substance found in crude human chorionic gonadotropin (hCG), induces proliferation of human peripheral blood lymphocytes (PBL) and cord blood cells (CBC) cultured in fetal calf serum (FCS). PAGF-induced proliferation requires both Ia+ non-T accessory cell(s) and T4 cells and phenotypic analysis of unfractionated PBL and CBC cultured with PAGF shows T3 expansion confined to the T4 but not T8 subset. PAGF is also a T-dependent polyclonal activator of B cells which favors IgM plaque-forming cells compared to IgG, using the staphylococcal protein A (pA-SRBC) reverse hemolytic plaque assay. This proposal concentrates on the purification of PAGF from crude hCG and pregnancy urine; the production of anti-PAGF antibodies and the development of an immunoassay for PAGF. To assess the biological role of PAGF, the PAGF-induced immunoregulatory circuit will be characterized in normal PBL, maternal PBL, and CBC phenotypically and functionally. Preliminary studies indicate PAGF has 2 peaks of activity on DEAE and reverse phase HPLC and can be separated chromatographically from contaminating mitogens for murine 3T3 fibroblasts and procine endothelial cells. It is not contaminated with hCG, immunosuppressive activity, interleukins 1, 2, or 3, or interferon when examined in appropriate bioassays. PAGF purified from pregnancy urine will be compared to hCG derived PAGF to see they are functionally and chemically the same. The results of this proposal should help to define whether PAGF is a normal growth factor or mitogen, present in normal urine or pregnancy "unique"; confirm its specificity for immunocompetent cells and define the immunoregulatory circuit involved. The immunoassay will initially quantitate PAGF in the blood and urine of normal and pregnant individuals and, if promising, will be applied to disease states with altered immune regulation such as autoimmunity, neoplasia and immunodeficiency. In addition, crude hCG provides an unappreciated, underutilized source of other uncharacterized growth factors necessary for fetal development and/or differentiation.